Short answer: IPv4 vs IPv6 is mainly a difference in address size, address format, and network behavior. IPv4 uses 32-bit addresses and still powers much of the internet. IPv6 uses 128-bit addresses, gives networks far more address space, and changes how devices, routers, DNS, VPNs, and firewalls behave.
For most users, the practical question is not which version is "better" in theory. It is whether your ISP, router, device, browser, VPN, DNS resolver, and the website you are visiting all handle the same IP version cleanly.
Quick answer
- IPv4 uses addresses like
203.0.113.7and often relies on NAT because public IPv4 space is limited. - IPv6 uses addresses like
2001:db8::1and has a much larger address space. - Dual-stack means a device or network can use IPv4 and IPv6 side by side.
- IPv6 is not automatically faster or safer. Real results depend on routing, DNS, firewall, VPN, and device configuration.
- Leak checks matter. A VPN can handle IPv4 correctly while IPv6, DNS, or WebRTC behaves differently.
IPv4 vs IPv6 at a glance
| Feature | IPv4 | IPv6 | What it means for users |
|---|---|---|---|
| Address size | 32-bit | 128-bit | IPv6 has vastly more possible addresses |
| Example | 203.0.113.7 | 2001:db8::1 | The formats look different and are configured differently |
| Address shortage | Public IPv4 space is scarce | Address space is much larger | IPv4 often needs NAT or CGNAT; IPv6 can assign more addresses directly |
| NAT use | Common on home and carrier networks | Usually not required for address conservation | IPv6 still needs firewalling even without NAT |
| Configuration | DHCP, static settings, NAT, private ranges | SLAAC, DHCPv6, router advertisements, privacy addresses | Devices may have several IPv6 addresses at once |
| Compatibility | Works almost everywhere | Depends on ISP, router, device, app, DNS, and website support | Most transitions use dual-stack or translation |
| Privacy behavior | Often hidden behind shared public IPv4 or NAT | Can use stable, temporary, link-local, or unique local addresses | Scope and address type matter more than the label alone |
How IPv4 works
IPv4 is the older internet protocol described in RFC 791. Its familiar dotted format uses four decimal numbers, such as 192.0.2.10. The address space is limited, so public IPv4 addresses are scarce.
Most home networks handle that scarcity with private IPv4 addresses and NAT. Your laptop might use 192.168.1.25 inside the home, while websites see the router's public IPv4 address. Your mobile carrier or ISP may also use carrier-grade NAT, which means many customers share public IPv4 space through another provider-side translation layer.
IPv4 remains important because almost every network, device, and website supports it. Even when IPv6 is enabled, IPv4 often remains active as a fallback or parallel route.
How IPv6 works
IPv6 is the newer internet protocol specified in RFC 8200. It uses 128-bit addresses written as colon-separated hexadecimal groups. The larger space lets providers assign much larger prefixes to networks and devices.
IPv6 addressing is more than "a longer IP." A device can have a global IPv6 address, a link-local fe80::/10 address, a unique local fc00::/7 address, and temporary privacy addresses, depending on the network. RFC 4291 defines IPv6 addressing architecture, while RFC 4862 covers stateless address autoconfiguration.
Some networks use SLAAC, some use DHCPv6, and many use both. Temporary address extensions, described in RFC 8981, can reduce long-term correlation from stable interface identifiers.
7 differences that matter in real life
- Address availability: IPv6 has enough address space for modern networks without relying on IPv4-style scarcity workarounds.
- NAT expectations: IPv4 networks commonly use NAT. IPv6 usually does not need NAT for address conservation, but firewalls still matter.
- Device addressing: IPv6 devices may have several addresses with different scopes and lifetimes.
- DNS behavior: IPv4 uses A records; IPv6 uses AAAA records. A domain can publish one, both, or neither.
- VPN behavior: some VPNs support IPv4 only, some support both, and some block IPv6 to prevent unsupported routes.
- Troubleshooting: a site can fail on IPv6 while working on IPv4, or the reverse, depending on routing and DNS.
- Privacy interpretation: neither protocol makes a user anonymous. Address scope, rotation, accounts, cookies, DNS, browser signals, and provider records all matter.
When IPv4 vs IPv6 matters most
The IPv4 vs IPv6 difference matters most when a real connection problem points to one protocol path and not the other. If every site works, you usually do not need to chase the protocol label. If one app, website, VPN route, or router feature behaves strangely, the IP version can tell you where to look next.
- A website works on one network but not another. The site may have an IPv6 routing, DNS, firewall, or CDN issue, even though IPv4 still works.
- A VPN leak test shows IPv6 outside the tunnel. That usually means the VPN does not tunnel IPv6, does not block unsupported IPv6, or is configured differently from the IPv4 route.
- Remote access fails. IPv4 port forwarding, CGNAT, router firewall rules, and IPv6 global reachability are different troubleshooting paths.
- Gaming, video calls, or smart-home devices behave inconsistently. Dual-stack networks can choose different routes for DNS, peer discovery, and direct connections.
- Geolocation or ASN results look wrong. IPv4 and IPv6 addresses can come from different provider pools, regions, or routing arrangements.
- A device has several IPv6 addresses. Link-local, global, temporary, and unique local addresses have different scopes, so they should not be interpreted as the same kind of exposure.
A careful IPv4 vs IPv6 check compares the browser result, DNS route, VPN status, WebRTC candidates, router WAN page, and device interface. That gives a better troubleshooting picture than treating one address shown by one tool as the whole network story.
Is IPv6 faster than IPv4?
Sometimes, but not as a rule. Speed depends on the ISP route, peering, DNS choice, device support, router firmware, Wi-Fi quality, VPN configuration, and the website's own network. A well-routed IPv6 path can be faster than IPv4. A poorly routed IPv6 path can be slower or less stable.
The practical answer is to test your own connection. If a website feels slow, compare IPv4 and IPv6 only when you can isolate the variable. Do not assume IPv4 vs IPv6 performance from a single page load, because DNS cache, browser cache, Wi-Fi, and server load can distort the result.
For a fair check, test the same device, the same network, and the same destination while changing only one factor at a time. A speed-test number alone is not enough; latency, packet loss, route stability, DNS delay, and app behavior may matter more than raw download speed. If a problem appears only on one protocol version, document the time, network, VPN state, DNS resolver, browser, and destination before changing router settings.
Is IPv6 safer or more private?
IPv6 is not safer by default, and IPv4 is not unsafe by default. Security comes from patching, firewall rules, router behavior, device settings, DNS choices, and account hygiene. IPv6 can reduce address-sharing complexity, but it can also expose globally routable addresses if firewall rules are wrong.
NAT in IPv4 can reduce some direct inbound reachability during normal home use, but NAT should not be treated as a complete security layer. IPv6 networks should use sensible firewalling rather than relying on address translation. If privacy is the concern, pay attention to temporary IPv6 addresses, browser fingerprints, DNS, WebRTC, accounts, and VPN behavior.
How DNS, VPNs, and WebRTC change the picture
DNS can return IPv4 A records, IPv6 AAAA records, or both. Browsers and operating systems may prefer one route, retry another, or use whichever route is faster and reachable. That is why a site may load over IPv6 even when you expected IPv4, or fall back to IPv4 when IPv6 is broken.
VPNs add another layer. A VPN may tunnel IPv4 and IPv6, tunnel IPv4 only, block IPv6, or expose different DNS behavior. That does not prove the VPN is unsafe by itself, but it means you should verify the route instead of assuming. WebRTC can also expose browser network candidates in some setups, so compare page IP, DNS, WebRTC, and IPv6 signals together.
How to check whether you use IPv4, IPv6, or both
- Open What Is My IP and note whether the visible address is IPv4, IPv6, or both.
- Run IPv6 Leak Test to see whether IPv6 is reachable in this browser session.
- Run DNS Leak Test and check whether resolvers match your expected route.
- Run WebRTC Leak Test if you use a VPN, proxy extension, conferencing tool, or privacy-focused browser profile.
- Use VPN Leak Test after connecting a VPN to compare IP, DNS, WebRTC, IPv6, and browser signals together.
- Check your router WAN status and device network settings if browser results do not match what you expected.
These checks are snapshots. One browser test does not prove every app on the device uses the same route, and it does not replace router, OS, VPN, or firewall review.
What to do if IPv6 causes problems
- Check router firmware and ISP status first. Broken IPv6 can come from router bugs, ISP rollout issues, DNS, or a stale configuration.
- Check firewall rules. IPv6 firewall rules are separate from IPv4 rules on many routers and operating systems.
- Check VPN support. If the VPN does not support IPv6, use the provider's recommended leak protection or blocking mode.
- Compare Wi-Fi and mobile data. One network may support IPv6 while another does not.
- Disable IPv6 only as temporary troubleshooting. Prefer fixing router, ISP, DNS, or VPN behavior for the long term.
If you manage the router, record the original settings before changing IPv6, DNS, firewall, or prefix delegation options.
What to do next
If your connection works over both versions, leave dual-stack alone and keep your router, OS, browser, and VPN updated. If IPv6 works but IPv4 does not, check DNS and legacy app support. If IPv4 works but IPv6 does not, check router advertisements, ISP support, firewall rules, DNS AAAA records, and VPN handling.
The practical value of understanding IPv4 vs IPv6 is knowing what layer failed. Address format problem? Check device settings. Website only fails on IPv6? Check DNS and routing. VPN route looks strange? Compare IP, DNS, WebRTC, and IPv6 together. Remote access behaves differently? Check firewalling, CGNAT, and whether the device has a global IPv6 address.
Frequently asked questions
What is the main difference between IPv4 and IPv6?
IPv4 uses 32-bit addresses written like 203.0.113.7. IPv6 uses 128-bit addresses written in hexadecimal groups, such as 2001:db8::1. The larger IPv6 space is the biggest technical difference, but privacy, NAT, DNS, routing, and firewall behavior also matter.
Is IPv6 faster than IPv4?
Not automatically. IPv6 can be faster, slower, or about the same depending on the ISP, route, device, DNS, peering, and the website. Measure the actual connection instead of assuming one version is always faster.
Is IPv6 safer than IPv4?
IPv6 is not safer by default. It uses different addressing and usually less NAT, but it still needs router firewalling, device updates, sensible DNS, and careful VPN behavior. Security depends on configuration, not just the IP version.
Should I disable IPv6 if my VPN has a leak?
Use disabling only as temporary troubleshooting if needed. A better long-term fix is to use a VPN/router setup that handles IPv6 correctly, blocks unsupported IPv6 routes, or clearly documents its IPv6 behavior.
How do I check whether I am using IPv4, IPv6, or both?
Use What Is My IP and IPv6 Leak Test to see what this browser exposes. Then compare DNS, WebRTC, VPN, and router settings because browser results, OS interfaces, and app traffic can differ.
Sources and methodology
MyIPScan tools and examples show observable browser and network signals. IP and geolocation results can be approximate, and VPN, DNS, WebRTC, IPv6, ASN, reputation, and browser checks are snapshots. A single result does not prove complete privacy or security. See the MyIPScan methodology and editorial policy.
This FAQ was updated using MyIPScan editorial guardrails: clear IPv4/IPv6 definitions, no speed or privacy guarantees, no VPN anonymity claims, no unsafe scanning advice, and primary technical sources for IPv4, IPv6, IPv6 addressing, SLAAC, DHCPv6, and temporary IPv6 addresses.